The present invention relates to a condenser suitable for use in, for example, a car air conditioner which is a refrigeration cycle mounted on an automobile.
Herein and in the appended claims, the upper side, lower side, left-hand side, and right-hand side of FIGS. 1, 8, and 11 will be referred to as “upper,” “lower,” “left,” and “right,” respectively.
The present applicant has proposed a condenser for a car air conditioner (see the pamphlet of WO2010/047320). The proposed condenser has a condensation section, a super-cooling section provided below the condensation section, and a liquid receiving section disposed in such a manner that its longitudinal direction coincides with the vertical direction. The condensation section includes at least two refrigerant condensation paths each formed by a plurality of heat exchange tubes disposed in parallel such that their longitudinal direction coincides with the left-right direction and they are spaced from one another in the vertical direction. The super-cooling section includes at least one refrigerant super-cooling path formed by a plurality of heat exchange tubes disposed in parallel such that their longitudinal direction coincides with the left-right direction and they are spaced from one another in the vertical direction. The refrigerant flowing out of the heat exchange tubes of the refrigerant condensation path at the lower end flows into the heat exchange tubes of the refrigerant super-cooling path at the upper end through the liquid receiving section. The condensation section includes the at least two refrigerant condensation paths and a condensation section outlet header section with which downstream end portions (in the refrigerant flow direction) of the heat exchange tubes of the refrigerant condensation path at the lower end communicate. The super-cooling section includes the at least one refrigerant super-cooling path and a super-cooling section inlet header section which is located on the same side as the condensation section outlet header section in the left-right direction and is located below the condensation section outlet header section. Upstream end portions (in the refrigerant flow direction) of the heat exchange tubes of the refrigerant super-cooling path at the upper end communicate with the super-cooling section inlet header section. The lower end of the liquid receiving section is located below the lower end of the condensation section outlet header section, and the upper end of the liquid receiving section is located above the lower end of the condensation section outlet header section. A first header tank and a second header tank are disposed at the left end or right end of the condenser in such a manner that the second header tank is located on the outer side of the first header tank in the left-right direction. The heat exchange tubes of the condensation section, excluding the heat exchange tubes of the lower-end refrigerant condensation path, are connected to the first header tank. The heat exchange tubes of the lower-end refrigerant condensation path of the condensation section and all the heat exchange tubes of the super-cooling section are connected to the second header tank. The lower end of the second header tank is located below the lower end of the first header tank, and the upper end of the second header tank is located above the lower end of the first header tank. The heat exchange tubes of the lower-end refrigerant condensation path of the condensation section and all the heat exchange tubes of the super-cooling section are connected to a portion of the second header tank located below the lower end of the first header tank. The condensation section outlet header section and the super-cooling section inlet header section are provided in the portion of the second header tank located below the lower end of the first header tank in such a manner that the former is located above the latter and the former and the latter communicate with each other. The second header tank also functions as the liquid receiving section.
In the condenser disclosed in the above-mentioned publication, the state of the refrigerant in the lower-end refrigerant condensation path becomes approximately the same as the state of the refrigerant in the second header tank, and the refrigerant is super cooled slightly even in the lower-end refrigerant condensation path.
Incidentally, the size of such a condenser must be decreased in some cases because of the restriction on the layout of the condenser in relation to other devices in the engine room of an automobile. For example, in an automobile on which an engine with a supercharger is mounted, a charge air cooler is generally used so as to cool compressed intake air to thereby increase the density of the intake air and improve the combustion efficiency of the engine. The charger are cooler may be disposed on the front side of a radiator to be located below the condenser. In such a case, the size of the condenser must be decreased.
Reducing the size of the condenser results in an increase in heat exchange load. In the case where the size of the condenser disclosed in the above-described publication is reduced, the super-cooling region is fixedly determined by the number of tubes inserted into the second header tank, whereby the condensation region may become insufficient. Therefore, it is expected that the condensation section fails to exhibit sufficient condensation performance under a specific condition regarding changes of an external environment such as temperature and wind speed.